This invention relates generally to inflatable passive restraint systems for use in vehicles for restraining the movement of a seated occupant during a collision and, more particularly, to an improvement in the structure such as used for housing and positioning a gas generator and inflatable bag in the vehicle.
The value of safety restraint systems which self-actuate from an undeployed to a deployed state without the need for intervention by the operator, i.e., "passive restraint systems", and particularly those restraint systems incorporating inflatable bags or cushions has gained general appreciation.
It is well known to protect a vehicle occupant using a cushion or bag that is inflated with gas, e.g., an "air bag" when the vehicle encounters sudden deceleration, such as in a collision. During deployment, the rapidly evolving gas with which the bag is typically filled is an inert gas, e.g., nitrogen. In such systems, the cushion is normally housed in an uninflated and folded condition to minimize space requirements.
Vehicular inflatable restraint systems generally include multiple crash sensors generally positioned about or mounted to the frame and/or body of the subject vehicle and serve to sense sudden decelerations by the vehicle. In turn, the sensor sends a signal to an inflatable bag module/assembly strategically positioned within the riding compartment of the vehicle to actuate deployment of the air bag. In general, an inflatable bag provided for the protection of a vehicle driver, i.e., a driver side air bag, is mounted in a storage compartment located in the steering column of the vehicle. Whereas, an inflatable bag for the protection of a front seat passenger, i.e., a passenger side air bag, is typically mounted in the instrument panel/dash board of the vehicle.
Typical inflatable passive restraint systems for the passenger side make use of an air bag module which generally includes an outer reaction housing or canister. The reaction canister generally serves to support or contain other components of the air bag module, including what is referred to as an "air bag inflator" or, more briefly, as an "inflator." The inflator, upon actuation, acts to provide the gas to inflate the bag.
Such a reaction canister is commonly formed of a trough-shaped body part which may be extruded and cut to a desired length. Such a body part typically includes a pair of opposed side walls the ends of which are typically closed by end plate walls such as of flat aluminum sheets or having an extruded form. An example of a reaction canister in accordance with the prior art will be found in commonly assigned U.S. Pat. No. 4,941,678 of Lauritzen, et al.
As described above, the reaction canister of the restraint system is commonly positioned behind the instrument panel of a vehicle. With a so positioned reaction canister, the edges of the reaction canister may be within one inch or less of the back surface of the instrument panel. As a result, such as in the event of a low speed collision without deployment of the air bag, for example, the head or other part of the body of a vehicle occupant may make impact with the instrument panel and force the instrument panel against the relatively rigid edge of the typical reaction canister, with the force of such contact being transmitted to the occupant. In turn, such contact can result in injury to the vehicle occupant. In view thereof, the National Highway Safety Administration has imposed standards relating to vehicle occupant impact with vehicle instrument panels.
One approach to solving this problem has been to add flanges or rounded edges to the otherwise open edges of the reaction canister. This has helped to a degree but the reaction canister still remains very stiff and rigid.
Another approach has been to add a pattern of slots in the trough-like sidewall and in the associated end panels. While such an approach can help to soften the edges of the reaction canister it can also result in weakening the reaction canister. In turn, a weakened reaction canister can be more susceptible to deformation upon air bag inflation, commonly referred to as "bell-mouthing". In addition, the inclusion of such slots in the side or end walls of a reaction canister can create potential snag points upon which the stored or deploying air bag may undesirably snag, which can detrimentally effect performance of the restraint system.
Another approach has been to simply cut down the reaction canister, e.g., the sidewalls and end plates, thereby leaving the folded up air bag exposed to serve as an impact cushion even in an undeployed state. Such an approach suffers, however, as cut down reaction canisters generally leave the air bag unsupported and unprotected and thus more susceptible to damage.
Consequently, the need remains for an improved reaction canister having softened edges which yield to direct impact but appropriately resist lateral displacement.